The present application relates to vehicle doors and, more particularly, the present application relates to an apparatus and method for providing a sliding door mechanism.
A typical vehicle is manufactured with a plurality of doors. Each door is typically mounted on hinges within a door opening. Some larger vehicles have sliding doors that slide from an open position to a closed position. Thus egress and ingress of the vehicle is possible without requiring a large open area beside the vehicle to allow for pivoting of the door. This is particularly useful in parking lots where the area between the vehicles is typically not large enough to allow for full pivoting to open the doors. Moreover, such sliding doors also allow the vehicles to have larger door openings.
Accordingly, sliding doors provide access to large door openings without requiring a large area adjacent to the vehicle, which would be required for a door that pivots on its hinge. In one configuration, a power sliding door is supported and guided by an upper track, a center track and a lower track. An upper roller is attached to the power sliding door and travels in the upper track. A lower roller is attached to a lower portion of the sliding door and runs or travels in the lower track. A hinge and roller assembly is pivotally attached to a rear portion (e.g., towards the rear of the vehicle) of the door between the upper and lower portions of the door. The hinge and roller assembly is also received in the track to allow for sliding movement of the door.
In addition to the usage of sliding doors in vehicles, power drive systems have been implemented wherein automatic opening, closing, locking and unlocking of the sliding door is facilitated through a drive system coupled to the sliding door. Presently, some sliding doors are driven through cables attached to the forward and aft sides of the center roller hinge (e.g., a hinge mounted towards the center of the door with respect to the upper and lower edges of the same).
Power sliding door (PSD) units have traditionally been located (in minivans) in the vehicle body between the “C” pillar and the “D” pillar, a.k.a. the rear quarter panel. This packaging area is greatly sought after by original equipment manufactures (OEMs) to locate other items. These items might include rear air conditioning units, spare tires, tool kits for tire changes, or general storage for the vehicle owner.
When quarter panel mounted PSD units are used, OEMs must allow for two different assembly sequences: one for the manual sliding door, and one for the power sliding door. If a door mounted power sliding door unit is used, the impact on the rear quarter panel usage is greatly reduced since door systems are often assembled off line from the main assembly line.
One design for a power sliding door is disclosed in U.S. Pat. No. 4,887,390. As shown in U.S. Pat. No. 4,887,390, an opening and closing device for a sliding vehicle door is provided, wherein a driving mechanism is installed in the sliding vehicle door. The driving mechanism has an output drum and a cable wound by the output drum, wherein one end of the cable is secured to the vehicle body and another end of the cable is secured to the vehicle body. The sliding door shown in U.S. Pat. No. 4,887,390 is slidably supported by a guide rail provided in the vehicle body and the cable is located in the guide rail, wherein one end of the cable is engaged with the vehicle body at one end and the another end of the cable is engaged with the vehicle body at another end.
However, in order to provide the necessary opening and closing forces to the sliding door, the driving mechanism in the sliding door must accommodate for the varying forces required as the door slides along in the guide rail. More particularly, as the door traverses along the guide track, the amount of cable being wrapped up by the cable drum may vary with the amount of cable being wrapped off. In addition, as the door slides along the curved portion of the guide rail (e.g., during initial opening or end of closing) located at either the lower track or center track, a higher force needs to be applied to cables pulling the door along in its guide track. In addition, since the driving mechanism is located within the door, the available real estate for driving mechanism designs is extremely limited.
Accordingly, it is desirable to provide an apparatus and method for providing a sliding door mechanism wherein the mechanism is capable of being installed within the sliding door and provides the necessary opening and closing forces.